Cationic aluminum alkyl complexes incorporating amidinate ligands as polymerization catalysts

ABSTRACT

Non-transition metal containing Ziegler-Natta like catalysts are prepared and used for polymerization reactions. The catalysts are cationic aluminum amidinate compounds. The compounds successfully catalyze polymerization of unsaturated hydrocarbons such as alpha olefins and avoid the expense of transition metals and, as well, the environmental objections to the use of the same.

GRANT REFERENCE

Work for this invention was funded in part by a grant from the NationalScience Foundation, Grant No. NSF CHE94-13022(003). The Government mayhave certain rights in this invention.

CROSS REFERENCE TO A RELATED APPLICATION

This application is a division of Ser. No. 08/818,297 filed Mar. 14,1997 now U.S. Pat. No. 5,777,120.

BACKGROUND OF THE INVENTION

Ziegler-Natta type catalysts for polymerization of unsaturatedhydrocarbons, such as alpha olefins, have long been the state of the artcatalysts for such reactions. Typically, Ziegler-Natta type catalystsare composed of transition metal salts and aluminum alkyl compounds.While these catalysts are very effective and have a long-establishedrecord of use, they are not without drawbacks. For example, transitionmetals are expensive, potentially present some toxicity hazards, and tosome are environmentally objectionable. Therefore, continuing effortstowards development of other suitable olefin polymerization catalystshave occurred. For example, metallocene catalysts have been developedfor use in alpha olefin polymerization.

This invention has as its primary objective the development of catalystsfor polymerization of unsaturated hydrocarbons which successfullypolymerize without a transition metal moiety as part of the catalyst.

Another objective of the present invention is to prepare such catalystsin high yields and by use of convenient and practical synthetic methods.

A yet further objective of the present invention is a method ofpolymerizing unsaturated hydrocarbons using Ziegler-Natta like catalystsin the sense that the catalyst behaves similarly to Ziegler-Nattacatalysts, but yet avoids the use of transition metals.

The method and manner of accomplishing each of the above objectives, aswell as others, will become apparent from the detailed description ofthe invention which follows hereinafter.

SUMMARY OF THE INVENTION

The invention relates to novel catalysts, processes of synthesizing thecatalysts, and to olefin polymerization reactions using the catalysts.The catalysts are cationic aluminum amidinate compounds. These compoundsbehave similarly to Ziegler-Natta catalysts, but avoid the use oftransition metals.

DETAILED DESCRIPTION OF THE INVENTION

The formation of polyethylene from the reaction of neutral aluminumcompounds including Cl₂ AlCH(Me)AlCl₂ or (AlR₃)₂ with ethylene in thetemperature range 25 to 50° C. has been reported in Martin, H.;Bretinger, H. Makromol. Chem. 1992, 193, 1283. However, the reportedcatalytic activities are very low (1.6×10⁻¹ -3.8×10⁻⁴ g PE/(mol*h*atm)).

After extensive work with transition metal catalysts and investigationinto the polymerization of unsaturated hydrocarbons such as olefins witha view to improving on the conventional processes by eliminatingtransition elements, a process has been discovered for polymerizing suchunsaturated hydrocarbons with an entirely new class of catalystcompounds.

The catalysts are cationic aluminum amidinate compounds of the followingformula: ##STR1## wherein R¹, R² and R³ are selected from the groupconsisting of C₁ to C₅₀ alkyl, aryl, or silyl groups, X is an anionicligand, n=0 or 1, L is a labile Lewis base or donor ligand or a neutralaluminum species capable of coordination, and A⁻ is a counterbalancingnon-coordinating or weakly coordinating anion.

The amidinate ligands (in anionic form) may be represented by structureC, which is the resonance hybrid of localized resonance structures A andB. Similarly, the base-free cationic aluminum complexes (n=0) may berepresented by structure F, which is the resonance hybrid of localizedresonance structures D and E. The situation for the base-stabilizedcationic aluminum complexes (n=1) is analogous. ##STR2## In the abovedescription of the resonance structures, R¹, R² and R³ are as earlierdescribed. With regard to the invention, while they broadly can be C₁ toC₅₀, generally speaking, preferred R¹, R² and R³ groups are C₁ to C₁₂alkyl, aryl or silyl.

The X moiety can represent a hydride radical, a dialkylamido radical, analkoxide radical, an aryloxide radical, a hydrocarbyl radical, asubstituted hydrocarbyl radical, a halocarbyl radical, or a thiolateradical. L is, of course, labile and can be displaced by other Lewisbases or donor ligands, including olefins, di-olefins, or any otherunsaturated monomer.

The A⁻ moiety represents the non-coordinating or weakly coordinatingcounterbalancing anion. In particular, it represents a compatible,non-coordinating anion containing a single coordination complexcomprising a charge-bearing metal or metalloid core which is relativelylarge (bulky), capable of stabilizing the active catalyst species andbeing sufficiently labile to be displaced by olefinic, di-olefinic oracetylenically unsaturated substrates, or other neutral Lewis bases ordonor groups, such as ethers, nitrites and the like. Polyhedral boraneanions, carborane anions and metallocarborane anions are also usefulnon-coordinating or weakly coordinating counterbalancing anions.

The key to proper anion design requires that the anionic complex islabile and stable toward reactions in the final catalyst species. Anionswhich are stable toward reactions with water or Bronsted acids and whichdo not have acidic protons located on the exterior of the anion (i.e.anionic complexes which do not react with strong acids or bases) possessthe stability necessary to qualify as a stable anion for the catalystsystem. The properties of the anion which are important for maximumlability include overall size, and shape (i.e. large radius ofcurvature), and nucleophilicity.

Using these guidelines one can use the chemical literature to choosenon-coordinating anions which can serve as components in the catalystsystem. In general, suitable anions for the second component may be anystable and bulky anionic complex having the following molecularattributes: 1) the anion should have a molecular diameter about orgreater than 4 angstroms; 2) the anion should form stable salts withreducible Lewis Acids and protonated Lewis bases; 3) the negative chargeon the anion should be delocalized over the framework of the anion or belocalized within the core of the anion; 4) the anion should be arelatively poor nucleophile; and 5) the anion should not be a powerfulreducing or oxidizing agent. Anions meeting these criteria--such aspolynuclear boranes, carboranes, metallacarboranes, polyoxoanions andanionic coordination complexes are well described in the chemicalliterature.

Illustrative, but not limiting examples of non-coordinating or weaklycoordinating counterbalancing anions are tetra(phenyl)borate,tetra(p-tolyl)borate, tetra(pentafluorophenyl)borate,tetra(3,5-bis-trifluoromethyl-phenyl)borate,(methyl)tris(pentafluorophenyl)borate, C₂ B₉ H₁₂ -, CB₁₁ H₁₂ -, B₁₂ H₁₂²⁻, and (C₂ B₉ H₁₁)₂ Co⁻.

As earlier stated, generally, these anions are (1) labile and can bedisplaced by an olefin, di-olefin or acetylenically unsaturated monomer,have a molecular diameter about or greater than 4 angstroms, form stablesalts with reducible Lewis acids and protonated Lewis bases, have anegative charge delocalized over the framework on the anion of which thecore thereof is not a reducing or oxidizing agent, and are relativelypoor nucleophiles. For other examples of such counterbalancing,non-coordinating or weakly coordinating anions, see Strauss, S. H.;Chemical Reviews, 1993, 93, 927-942.

L, the optional labile Lewis base ligand, is also conventional and wellknown. It can, for example, be represented by tetrahydrofuran, etherssuch as dimethyl ether, amines, alkyl amines, pyridine, substitutedpyridines, and phosphines. L may also be represented by a neutralaluminum species which coordinates to the cation through a bridginggroup, such as {MeC(N^(i) Pr)₂ }AlMe₂ ; AlMe₃ ; and AlCl₃. The presenceof such neutral coordinating ligands L is not critical, and they may ormay not be present as deemed appropriate in any particular reaction.

The cationic aluminum amidinate complexes may be prepared by reacting aneutral precursor complex of the type {R² C(NR¹)(NR³)}AlX₂, where R¹,R², R³, and X are as defined above, with an activator compound which iscapable of abstracting one X⁻ group from the precursor complex or ofcleaving one Al--X bond of the precursor complex. Suitable activatorcompounds include Bronsted acids, such as ammonium salts, Lewis acids,such as AlCl₃ and B(C₆ F₅)₃, ionic reagents such as Ag⁺ and tritylsalts, and oxidizing agents such as ferrocenium salts. Illustrative, butnot limiting examples of suitable activator compounds areN,N-dimethylanilinium tetra(pentafluorophenyl)borate,methyldiphenylammonium tetra(pentafluorophenyl)borate, aluminumtrichloride, tris(pentafluorophenyl)boron, silver (I)tetra(phenyl)borate, triphenylcarbenium tetra(pentafluorophenyl)borate,and ferrocenium tetra(phenyl)borate.

The synthesis of the catalyst compounds as earlier described for thepresent invention is particularly straightforward. Ideally, they areprepared on a high vacuum line under an inert atmosphere in the presenceof solvents in the manner illustrated in the examples below. Theseexamples of synthesis are illustrative and not intended to be limitingof the invention.

All manipulations were performed on a high-vacuum line or in a glove boxunder a purified N₂ atmosphere. Solvents were distilled fromNa/benzophenone ketyl, except for chlorinated solvents, which weredistilled from activated molecular sieves (3 Å) or P₂ O₅.

NMR spectra were recorded on a Bruker AMX 360 spectrometer in sealed orTeflon-valved tubes at ambient probe temperature unless otherwiseindicated. ¹ H and ¹³ C chemical shifts are reported versus SiMe₄ andwere determined by reference to the residual ¹ H and ¹³ C solvent peaks.All coupling constants are reported in Hz. The NMR spectra of cationiccomplexes contained resonances for B(C₆ F₅)₄ ⁻ or [B(C₆ F₅)₃ Me]⁻.

NMR data for B(C₆ F₅)₄ -: ¹³ C NMR (CD₂ Cl₂): δ 148.6 (d,¹ JCF=240.0Hz), 138.7 (d,¹ JCF=245.4 Hz), 136.8 (d,¹ JCF=245.4 Hz), 124.7 (br s,ipso-Ph). NMR data for MeB(C₆ F₅)₃ -: ¹ H NMR (CD₂ Cl₂): δ 0.47 (br s,3H, B--CH₃). ¹³ C NMR (CD₂ Cl₂): δ 148.6 (d, ¹ JCF=235.5 Hz), 137.9 (d,¹JCF=242.7 Hz), 136.8 (d,¹ JCF=246.4 Hz), 129.7 (br s, ipso-Ph), 10.34(br s, B--CH₃).

Mass spectra were obtained using the Direct Insertion Probe (DIP)method, on a VG Analytical Trio I instrument operating at 70 eV.Elemental analyses were performed by Desert Analytics Laboratory.

EXAMPLE 1 {MeC(N^(i) Pr)₂ }AlMe₂

A solution of 1,3-diisopropylcarbodimide (2.00 g, 10.7 mmol) in hexane(25 mL) was added dropwise via pipette to a rapidly stirred solution ofAlMe₃ (1.06 mL, 11.0 mmol) in hexane (10 mL). An exothermic reactionswas observed. The reaction mixture was stirred at room temperature for18 h, after which time the volatiles were removed under vacuum affordingpure {MeC(N^(i) Pr)₂ }AlMe₂ as a pale yellow liquid (2.30 g, 71%). ¹ HNMR (CD₂ Cl₂): δ 3.50 (sept,³ J_(HH) =6.3 Hz, 2H, CHMe₂), 1.94 (s, 3H,CMe), 1.05 (d,³ J_(HH) =6.1 Hz, 12H, CHMe₂),-0.82 (s, 6H, AlMe₂). ¹³ CNMR (CD₂ Cl₂): δ 172.5 (s, CMe), 45.3 (d,¹ J_(CH) =132.2 Hz, CHMe₂),25.3 (q, ¹ J_(CH) =125.6 Hz, CHMe₂), 11.1 (q,¹ J_(CH) =128.3 Hz,CMe),-9.94 (br q), ¹ J_(CH) =114.1 Hz, ALMe₂). Anal. Calcd for C₁₀ H₂₃N₂ Al: C, 60.57; H, 11.69; N, 14.13. Found: C, 60.41; H, 11.96; N,14.50.

EXAMPLE 2 {MeC(NCy)₂ }AlMe₂

A solution of 1,3-dicyclohexylcarbodiimide (5.00 g, 24.2 mmol) in hexane(40 mL) was added slowly to a solution of AlMe₃ (2.40 mL, 25.0 mmol) inhexane (15 mL). The solution was stirred for 15 h and the volatiles wereremoved under vacuum yielding a pale yellow liquid that crystallizedupon standing to afford pure {MeC(NCy)₂ }AlMe₂ as off-white crystals.(6.49 g, 93%). ¹ H NMR (CD₂ Cl₂): δ 3.10 (m, 2H, Cy), 1.92 (s, 3H, CMe),1.69 (m,8H,Cy),1.56(m,2H,Cy),1.35-1.06(m,8H+2H,Cy),-0.82(s,6H,ALMe₂). ¹³C NMR (CD₂ Cl₂): δ 172.4(s,CMe), 53.0(d,¹ J_(CH) =131.4 Hz,Cy-C₁),36.0(t,¹ J_(CH) =126.5 Hz,Cy), 26.1 (t,¹ J_(CH) =125.8 Hz,Cy), 25.4 (t,¹J_(CH) =126.9 Hz,Cy), 11.2 (q,¹ J_(CH) =128.0 Hz, CMe),-9.78 (br q),¹J_(CH) =112.6 Hz, AlMe₂). Anal. Calcd for C₁₆ H₃₁ N₂ Al: C, 69.02; H,11.22; N, 10.06. Found: C, 68.88; H, 10.44; N, 10.15. Mass Spec. (EI,m/z): 263 [M]⁺.

EXAMPLE 3 Li[^(t) BuC(N^(i) Pr)₂ ]

A solution of 1,3-diisopropylcarbodimide (5.00 g, 39.6 mmol) in Et₂ O(50 mL) was cooled to 0° C. ^(t) BuLi(23.30 mL of a 1.7 M solution inpentane, 39.6 mmol) was added dropwise via syringe and the mixture wasallowed to warm to room temperature. After 30 min the solvent wasremoved under vacuum affording a yellow oily solid which was dried undervacuum (18 h, 23° C.) to give a pale yellow solid. Trituration withhexane gave Li[^(t) BuC(N^(i) Pr)₂ ] as an off-white powder (4.56 g,61%). ¹ H NMR (THF-d₈): δ 3.84 (sept, ³ J_(HH) =5.7 Hz, 2H, CHMe₂), 1.13(s, 9H, CMe₃), 0.96 (d, ³ J_(HH) =6.1 Hz, 12H, CHMe₂). ¹³ C NMR(THF-d₈): δ 168.5 (s, CCMe₃), 46.6 (d, ¹ J_(CH) =122.3 Hz, CHMe₂), 39.4(s, CMe₃), 31.0 (q,¹ J_(CH) =116.1 Hz, CHMe₂), 26.3 (q,¹ J_(CH) =116.1Hz, CMe₃).

EXAMPLE 4 Li[^(t) BuC(NCy)₂ ]

A solution of 1,3-dicyclohexylcarbodimide (5.00 g, 24.2 mmol) in Et₂ O(50 mL) was cooled to 0° C. ^(t) BuLi (14.3 mL of a 1.7 M solution inpentane, 24.2 mmol) was added via syringe and the mixture was allowed towarm to room temperature. After 30 min the volatile components wereremoved under vacuum affording a yellow oily solid which was driedovernight under vacuum to yield a pale yellow powder. Trituration ofthis solid with pentane gave Li[^(t) BuC(NCy)₂ ] as a pale yellow powder(4.91 g, 75%). ¹ H NMR (THF-d₈): δ 3.50 (m,2H,Cy), 1.81-0.93 (m,20H,Cy),1.10 (s,9H,CMe₃). ¹³ C NMR (THF-d₈): δ 168.3 (s,CCMe₃), 55.9 (d,¹ J_(CH)=119.8 Hz, Cy-C₁), 39.5 (s,CMe₃), 37.7 (t,¹ J_(CH) =118.9 Hz,Cy), 31.1(q,¹ J_(CH) =117.7 Hz,CMe₃), 28.2 (t, partially obscured, Cy), 26.8 (t,¹J_(CH) =119.4 Hz, Cy).

EXAMPLE 5 {^(t) BuC(N^(i) Pr)₂ }AlCl₂

A solution of AlCl₃ (1.40 g, 10.5 mmol) in Et₂ O (30 mL) was cooled to-78° C. and added dropwise to a slurry of Li[^(t) BuC(N^(i) Pr)₂ ] (2.00g, 10.5 mmol) in Et₂ O (50 mL) which was also at -78° C. The mixture waswarmed to room temperature and stirred for 16 h, affording a slurry of awhite solid in a yellow solution. The volatiles were removed undervacuum and the product was extracted from the LiCl with pentane.Concentration of the pentane extract and cooling to 0C afforded pure{^(t) BuC(N^(i) Pr)₂ }AlCl₂ as opaque white crystals which werecollected by filtration (2.01 g, 68%). ¹ H NMR (CD₂ Cl₂): δ 4.12 (brsept, ³ J_(HH) =5.9 Hz, 2H, CHMe₂), 1.43 (s,9H,CMe₃), 1.18 (d,³ J_(HH)=6.2 Hz, 12H, CHMe₂). ¹³ C NMR (CD₂ Cl₂): δ 184.3 (s, CCMe₃), 46.6 (d,¹J_(CH) =135.7 Hz, CHMe₂), 40.1 (s,CMe₃), 29.2 (q,¹ J_(CH) =125.7 Hz,CMe₃), 25.9 (q,¹ J_(CH) =124.1 Hz, CHMe₂). Anal. Calcd for C₁₁ H₂₃ N₂AlCl₂ : C, 46.98; H, 8.24; N, 9.96. Found: C, 46.84; H, 8.12; N, 9.85.Mass Spec. (EI,m/z,³⁵ Cl): 265 [M]⁺.

EXAMPLE 6 {^(t) BuC(NCy)₂ }AlCl₂

A solution of AlCl₃ (0.99 g, 7.4 mmol) in Et₂ O (25 mL) was addeddropwise to a slurry of Li[^(t) BuC(NCy)₂ ](2.00 g, 7.4 mmol) in Et₂ O(50 mL) at -78° C. The mixture was warmed to room temperature andstirred for 18 h, affording a slurry of a white precipitate in a yellowsolution. The volatiles were removed under vacuum and the product wasextracted from the LiCl with toluene. Concentration of the tolueneextract and cooling to 0° C. afforded pure {^(t) Bu(NCy)₂ }AlCl₂ ascolorless crystals which were collected by filtration (1.84 g, 69%). ¹ HNMR (CD₂ Cl₂): δ 3.62 (br m,2H,Cy), 1.41 (s,9H,CMe₃), 1.91-1.71(m,4H,Cy), 1.62 (m,2H,Cy), 1.30-1.09 (m,8H+2H,Cy). ¹³ C NMR (CD₂ Cl₂): δ184.4 (s,CCMe₃), 54.6 (d,¹ J_(CH) =138.7 Hz, Cy-C₁), 40.1 (s,CMe₃), 36.9(t,¹ J_(CH) =127.9 Hz,Cy), 29.3 (q,¹ J_(CH) =127.7 Hz, CMe₃), 25.7 (t,¹J_(CH) =125.7 Hz,Cy), 25.6 (t,¹ J_(CH) =125.7 Hz,Cy). Anal. Calcd forC₁₇ H₃₁ N₂ AlCl₂ : C, 56.51; H, 8.65; N, 7.75. Found: C, 56.22; H, 8.70;N, 7.67. Mass Spec. (EI,m/z,³⁵ Cl):360[M]⁺.

EXAMPLE 7 {^(t) BuC(N^(i) Pr)₂ }AlMe₂

A solution of AlMe₂ Cl (0.25 mL, 2.7 mmol) in Et₂ O (25 mL) was addeddropwise to a slurry of Li[^(t) BuC(N^(i) Pr)₂ ](0.50 g, 2.6 mmol) inEt₂ O (30 mL) at -78° C. The reaction mixture was allowed to warm slowlyto room temperature and was stirred for 18 h. The volatiles were removedunder vacuum and the residue was extracted with pentane. The extract wasevaporated to dryness under vacuum yielding {^(t) BuC(N^(i) pr)₂ }AlMe₂as a pale yellow solid (0.57 g, 87%). ¹ H NMR (CD₂ Cl₂): δ 4.07 (sept,³J_(HH) =6.2 Hz,2H,CHMe₂), 1.38 (s,9H,CMe₃), 1.06 (d,³ J_(HH) =6.1Hz,12H,CHMe₂), -0.81 (s,6H,ALMe₂). ¹³ C NMR (CD₂ Cl₂): δ 178.4(s,CCMe₃), 45.8 (d,¹ J_(CH) =135.3 Hz,CHMe₂), 40.0 (s,CMe₃), 29.7 (q,¹J_(CH) =127.0 Hz, CHMe₂), 26.3 (q,¹ J_(CH) =125.5 Hz,CMe₃), -9.06 (brq,¹ J_(CH) =117.7 Hz,AlMe₂). Anal. Calcd for C₁₃ H₂₉ N₂ Al: C, 64.96; H,12.16; N, 11.65. Found: C, 64.46; H, 11.90; N, 11.90. Mass Spec.(EI,m/z): 240 [M]⁺, 225 [M-CH₃ ]⁺.

EXAMPLE 8 {^(t) BuC(NCy)₂ }AlMe₂

A solution of AlMe₂ Cl (0.71 mL, 7.7 mmol) in Et₂ O (30 mL) was addeddropwise to a slurry of Li[^(t) BuC(NCy)₂ ](2.00 g, 7.4 mmol) in Et₂ O(40 mL) at -78° C. The mixture was allowed to warm to room temperatureand was stirred for 15 h. The volatiles were removed under vacuum andthe residue was extracted with pentane (3×15 mL). The extract wasconcentrated to 30 mL and maintained at room temperature affording {^(t)BuC(NCy)₂ }AlMe₂ (2.00 g, 83%) as large colorless crystals which werecollected by filtration.¹ H NMR (CD₂ Cl₂): δ 3.56 (m,2H,Cy), 1.80-1.69(m,8H,Cy), 1.61-1.57 (m,2H,Cy), 1.36 (s,9H,CMe₃), 1.27-1.03(m,8H+2H,Cy), -0.83 (s,6H,AlMe₂). ¹³ C NMR (CD₂ Cl₂): δ 178.5 (s,CCMe₃),54.2 (d,¹ J_(CH) =125.9 Hz, Cy-C₁), 39.9 (s,CMe₃), 37.3 (t,¹ J_(CH)=119.3 Hz,Cy), 29.7 (q,¹ J_(CH) =117.3 Hz,CMe₃), 26.1 (t,¹ J_(CH) =119.3Hz,Cy), 26.0 (t,¹ J_(CH) =119.3 Hz, Cy), -9.1 (br q,¹ J_(CH) =103.9Hz,AlMe₂). Anal. Calcd for C₁₉ H₃₇ N₂ Al: C, 71.20; H, 11.64; N, 8.74.Found: C, 71.18; H, 11.88; N, 8.73. Mass Spec. (EI,m/z): 320 [M]⁺, 305[M-CH₃ ]⁺.

EXAMPLE 9 {^(t) BuC(N^(i) Pr)₂ }Al(CH₂ Ph)₂

A solution of {^(t) BuC(N^(i) Pr)₂ }AlCl₂ (0.50 g, 1.8 mmol) in Et₂ O(25 mL) was cooled to -78° C. and PhCH₂ MgCl (3.56 mL of a 1.0 Msolution in Et₂ O, 3.6 mmol) was added dropwise via syringe. Thereaction mixture was allowed to warm to room temperature and was stirredfor 15 h. The volatiles were removed under vacuum and the residue wasextracted with pentane. The extract was evaporated to dryness undervacuum affording pure {^(t) BuC(N^(i) pr)₂ }Al(CH₂ Ph)₂ as a viscous oil(0.55 g, 79%) that can be induced to solidify through storage at -40° C.¹ H NMR (CD₂ Cl₂): δ 7.11 (t,³ J_(HH) =7.6 Hz,4H,m-Ph), 7.02 (d,³ J_(HH)=6.9 Hz,4H,o-Ph), 6.88 (t,³ J_(HH) =7.3 Hz,2H,p-Ph), 4.00 (sept,³ J_(HH)=6.2 Hz,2H,CHMe₂), 1.75 (s,4H,CH₂ Ph), 1.34 (s,9H,CMe₃), 0.94 (d,³J_(HH) =6.2 Hz, 12H, CHMe₂). ¹³ C NMR (CD₂ Cl₂): δ 180.8 (s,CCMe₃),146.8 (s,ipso-Ph), 128.2 (d,¹ J_(CH) =155.8 Hz, o- or m-Ph), 127.5 (d,¹J_(CH) =149.4 Hz, o- or m-Ph), 121.7 (d,¹ J_(CH) =148.5 Hz,p-Ph), 45.6(d,¹ J_(CH) =128.9 Hz,CHMe₂), 40.1 (s,CMe₃), 29.6 (q,¹ J_(CH) =119.0Hz,CMe₃), 26.3 (q,¹ J_(CH) =116.4 Hz,CHMe₂), 21.4 (br t,¹ J_(CH) =108.9Hz, CH₂ Ph). Anal. Calcd for C₂₅ H₃₇ N₂ Al: C, 76.49; H, 9.50; N, 7.14.Found: C, 75.05; H, 9.63; N, 6.89. Mass Spec. (EI,mlz): 301 [M-CH₂ Ph]⁺.

EXAMPLE 10 {^(t) BuC(NCy)₂ }Al(CH₂ Ph)₂

A solution of {^(t) BuC(NCy)₂ }AlCl₂ (0.50 g, 1.4 mmol) in Et₂ O (20 mL)was cooled to -78° C. and PhCH₂ MgCl (2.76 mL of a 1.0 M solution in Et₂O, 2.8 mmol) was added dropwise by syringe. The mixture was allowed towarm slowly to room temperature and was stirred for 15 h. The volatileswere removed under vacuum and the residue was extracted with pentane.The extract was evaporated under vacuum affording pure {^(t) BuC(NCy)₂}Al(CH₂ Ph)₂ as a viscous white oil. (0.57 g, 87%). ¹ H NMR (CD₂ Cl₂): δ7.08 (t,³ J_(HH) =7.6 Hz,4H,m-Ph), 6.98 (d,³ J_(HH) =6.9 Hz,4H,o-Ph),6.84 (t,³ J_(HH) =7.3 Hz,2H,p-Ph), 3.44 (m,2H,Cy), 1.69 (s,4H,CH₂ Ph),1.63-1.51 (m,4H+2H,Cy), 1.27 (s,9H,CMe₃), 1.21-0.78 (m,14H,Cy). ¹³ C NMR(CD₂ Cl₂): δ 180.8 (s,CCMe₃), 146.9 (s,ipso-Ph), 126.2 (d,¹ J_(CH)=155.8 Hz, o- or m-Ph), 127.5 (d,¹ J_(CH) =147.6 Hz, o- or m-Ph), 121.6(d,J_(CH) =151.3 Hz,p-Ph), 54.0 (d, partially obscured, Cy-C₁), 40.0(s,CMe₃), 37.1 (t,¹ J_(CH) =117.7 Hz,Cy), 29.6 (q,¹ J_(CH) =117.3Hz,CMe₃), 25.9 (t,¹ J_(CH) =118.2 Hz,Cy), 25.7 (t,¹ J_(CH) =118.2Hz,Cy), 21.4 (t,¹ J_(CH) =108.7 Hz,CH₂ Ph). Anal. Calcd for C₃₁ H₄₅ N₂Al: C, 78.77; H, 9.60; N, 5.93. Found: C, 78.62; H, 9.58; N, 5.83.

EXAMPLE 11 {^(t) BuC(N^(i) Pr)₂ }Al(CH₂ CMe₃)₂

{^(t) BuC(N^(i) Pr)₂ }AlCl₂ (0.50 g, 1.8 mmol) and LiCH₂ CMe₃ (0.28 g,3.6 mmol) were mixed as solids in the glove box. Et₂ O (40 mL) was addedat -78° C. and the mixture was allowed to warm slowly to roomtemperature, affording a colorless solution and a white precipitate. Themixture was stirred for 18 h and the volatiles were removed undervacuum. The residue was extracted with pentane (3×10 mL). The extractwas taken to dryness under vacuum affording {^(t) BuC(N^(i) Pr)₂ }Al(CH₂CMe₃)₂ as a white solid (0.58 g, 93%). ¹ H NMR (CD₂ Cl₂): δ 4.13 (sept,³J_(HH) =6.2 Hz, CHMe₂), 1.39 (s,9H,CMe₃), 1.15 (d,³ J_(HH) =6.3 Hz,CHMe₂), 0.99 (s,18H,CH₂ CMe₃), 0.27 (s,4H,CH₂ CMe₃). ¹³ C NMR (CD₂ Cl₂):δ 179.7 (s,CCMe₃), 46.1 (d,¹ J_(CH) =121.0 Hz,CHMe₂), 40.1 (s,CMe₃),35.2 (q,¹ J_(CH) =112.2 Hz, CH₂ CMe₃), 32.1 (br t, partially obscured,CH₂ CMe₃), 31.6 (s, CH₂ CMe₃), 29.8 (q,¹ J_(CH) =121.2 Hz,CMe₃), 26.6(q,¹ J_(CH) =117.9 Hz, CHMe₂). Anal. Calcd for C₂₁ H₄₅ N₂ Al: C, 71.54;H, 12.86; N, 7.95. Found: C, 70.46; H, 12.82; N, 7.72. Mass Spec.(EI,m/z): 281 [M-CH₂ CMe₃ ]⁺.

EXAMPLE 12 {^(t) BuC(NCy)₂ }Al(CH₂ CMe₃)₂

A solution of LiCH₂ CMe₃ (0.43 g, 5.5 mmol) in Et₂ O (20 mL) was addeddropwise at -78° C. to an Et₂ O solution (30 mL) of {^(t) BuC(NCy)₂}AlCl₂ (1.00 g, 2.8 mmol). The reaction mixture was allowed to warmslowly to room temperature and was stirred for 15 h. The volatiles wereremoved under vacuum and the residue was extracted with pentane. Theextract was evaporated to dryness under vacuum to afford pure {^(t)BuC(NCy)₂ }Al(CH₂ CMe₃)₂ as a white solid material (1.13 g, 94%). ¹ HNMR (CD₂ Cl₂): δ 3.63 (m,2H,Cy), 1.86-1.71 (m,8H,Cy), 1.60 (m,2H,Cy),1.36 (s,9H,CMe₃), 1.30-1.09 (m,8H+2H,Cy), 0.99 (s,CH₂ CMe₃), 0.25(s,4H,CH₂ CMe₃). ¹³ C NMR (CD₂ Cl₂): δ 179.7 (s,CCMe₃), 54.8 (d,¹ J_(CH)=126.8 Hz, Cy-C₁), 40.0 (s,CMe₃), 37.2 (t,¹ J_(CH) =124.3 Hz,Cy), 35.2(q,¹ J_(CH) =117.6 Hz, CH₂ CMe₃), 32.1 (br t, partially obscured, CH₂CMe₃), 31.6 (s,CH₂ CMe₃), 29.8 (q,¹ J_(CH) =119.6 Hz, CMe₃), 26.2 (t,¹J_(CH) =118.2 Hz, Cy), 26.1 (t,¹ J_(CH) =118.2 Hz, Cy). Anal. Calcd forC₂₇ H₅₃ N₂ Al: C, 74.95; H, 12.35; N, 6.47. Found: C, 73.87; H, 12.42;N, 6.60. Mass Spec. (EI,m/z): 362 [M-CH₂ CMe₃ ]⁺.

EXAMPLE 13 [({MeC(N^(i) Pr)₂ }AlMe)₂ (μ-Me)][MeB(C₆ F₅)₃ ]

A solution of B(C₆ F₅)₃ (0.77 g, 1.5 mmol) in CH₂ Cl₂ (20 mL) was addedto {MeC(N^(i) Pr)₂ }AlMe₂ (0.60 g, 3.0 mmol) also in CH₂ Cl₂ (15 mL).The reaction mixture was allowed to stir for 30 min at room temperatureand the volatiles were removed under vacuum leaving an oily white solid.Trituration with pentane afforded [({MeC(N^(i) Pr)₂ }AlMe)₂(μ-Me)][MeB(C₆ F₅)₃ ] as a white powder (0.91 g, 83%). ¹ H NMR (CD₂Cl₂,293 K): δ 3.79 (sept,³ J_(HH) =6.6 Hz,4H,CHMe₂), 2.31 (s,6H,CMe),1.28 (d,³ J_(HH) =6.5 Hz,24H,CHMe₂), -0.38 (br s,9H,AlMe). ¹ H NMR (CD₂Cl₂,193K): δ 3.79 (br sept,2H,CHMe₂), 3.67 (br sept,6H,CHMe₂), 2.33(s,6H,CMe), 2.15 (s,6H,CMe), 1.30 (m,18H,CHMe₂), 1.18 (m,12H,CHMe₂),1.02 (m,18H,CHMe₂), -0.17 (s, 6H, AlMe), -0.54 (s, 6H, AlMe), -0.75 (s,6H, AlMe). ¹¹ B NMR (CD₂ Cl₂): δ -13.4 (br s, MeB(C₆ F₅)₃). ¹³ C NMR(CD₂ Cl₂): δ 182.0 (s,CMe), 50.5 (d,¹ J_(CH) =138.9 Hz, CHMe₂), 23.4(q,¹ J_(CH) =127.0 Hz, CHMe₂) 17.8 (q,¹ J_(CH) =130.3 Hz, CMe), -5.6 (brq,¹ J_(CH) =130.3 Hz, AlMe). Anal. Calcd for C₃₈ H₄₆ N₄ Al₂ BF₁₅ : C,50.23; H, 5.10; N, 6.17. Found: C, 50.46; H, 4.92; N, 6.09.

EXAMPLE 14 [{MeC(N^(i) Pr)₂ }AlMe(NMe₂ Ph)][B(C₆ F₅)₄ ]

A CD₂ Cl₂ solution (600 μL) of [HNMe₂ Ph][B(C₆ F₅)₄ ] (85.3 mg, 0.11mmol) was added to a vial containing {MeC(N^(i) Pr)₂ }AlMe₂ (21.1 mg,0.11 mmol). The mixture was transferred to an NMR tube and NMR spectrawere recorded showing complete conversion to [{MeC(N^(i) Pr)₂ }AlMe(NMe₂Ph)][B(C₆ F₅)₄ ]. ¹ H NMR (CD₂ Cl₂ : δ 7.63 (t,³ J_(HH) =7.9Hz,2H,m-Ph), 7.51 (t,³ J_(HH) =7.3 Hz,1H,p-Ph), 7.47 (d,³ J_(HH) =7.9Hz,2H,o-Ph), 3.58 (sept,³ J_(HH) =6.4 Hz, 2H,CHMe₂), 3.20 (s, 6H, NMe₂Ph), 2.17 (s, 3H, CMe), 1.03 (d,³ J_(HH) =6.5 Hz, 6H, CHMe₂), 0.92 (d,³J_(HH) =6.4 Hz, 6H, CHMe₂), -0.30 (s, 3H, AlMe). ¹³ C NMR (CD₂ Cl₂): δ182.0 (s,CMe), 143.7 (s, ipso-Ph), 131.4 (d,¹ J_(CH) =159.4 Hz, o-Ph),129.8 (d,¹ J_(CH) =164.8 Hz, p-Ph), 120.9 (d,¹ J_(CH) =153.1 Hz, m-Ph),46.7 (q,¹ J_(CH) =134.7 Hz, NMe₂), 46.0 (d,¹ J_(CH) =125.2 Hz, CHMe₂),24.7 (q,¹ J_(CH) =119.7 Hz, CHMe₂), 24.6 (q,¹ J_(CH) =119.7 Hz, CHMe₂),12.7 (q,¹ J_(CH) =122.6 Hz, CMe), -13.4 (br q,¹ J_(CH) =116.8 Hz, AlMe).

EXAMPLE 15 [{MeC(N^(i) Pr)₂ }AlMe(PMe₃)][MeB(C₆ F₅)₃ ]

A CD₂ Cl₂ solution of [({MeC(N^(i) Pr)₂ }AlMe)₂ (μ-Me)][MeB(C₆ F₅)₃ ]was cooled in liquid N₂ and PMe₃ (5 equiv) was condensed onto the frozensolution. The mixture was warmed to room temperature and the ¹ H NMRspectrum was recorded, showing that complete formation of thetrimethylphosphine adduct [{MeC(N^(i) Pr)₂ }AlMe(PMe₃)][MeB(C₆ F₅)₃ ]and {MeC(N^(i) Pr)₂ }AlMe₂ had occurred. To obtain a sample free fromreaction byproducts, the NMR tube was evacuated and pumped on for 18 h.The resulting oily solid was redissolved in CD₂ Cl₂ and the NMR spectrawas recorded, and showed that only [{MeC(N^(i) Pr)₂ }AlMe(PMe₃)][MeB(C₆F₅)₃ ] was present. ¹ H NMR (CD₂ Cl₂): δ 3.62 (sept,³ J_(HH) =6.3 Hz,2H, CHMe₂), 2.17 (s, 3H, CMe), 1.52 (d,² J_(PC) =9.4 Hz, 9H, PMe₃), 1.10(d,³ J_(HH) =6.3 Hz, 12H, CHMe₂), -0.27 (s, 3H, AlMe). ³¹ P NMR (CD₂Cl₂): δ -34.55 (s,PMe₃). ¹³ C NMR (CD₂ Cl₂): δ 180.6 (s, CMe), 45.5 (d,¹J_(CH) =131.1 Hz, CHMe₂), 25.3 (q,¹ J_(CH) =121.0 Hz, CHMe₂), 12.4 (q,¹J_(CH) =124.7 Hz, CMe), 9.1 (dq,¹ J_(PC) =29.6 Hz,¹ J_(CH) =127.6 Hz,PMe₃), -12.8 (br q,¹ J_(CH) =109.6 Hz, AlMe).

EXAMPLE 16 [{MeC(N^(i) Pr)₂ }AlMe(PMe₃)][B(C₆ F₅)₄ ]

A CD₂ Cl₂ solution of [{MeC(N^(i) Pr)₂ }AlMe(NMe₂ Ph)] [B(C₆ F₅)₄ ] wascooled in liquid N₂ and PMe₃ (5 equiv) was condensed onto the frozensolution. The mixture was warmed to room temperature and the ¹ H NMRspectrum was recorded, showing that formation of the trimethylphosphineadduct [{MeC(N^(i) Pr)₂ }AlMe(PMe₃)][B(C₆ F₅)₄ ] and free NMe₂ Ph hadoccurred. 1H NMR (CD₂ Cl₂): δ 3.62 (sept, ³ JHH=6.3 Hz, 2H, CHMe₂), 2.17(s, 3H, CMe), 1.52 (d, ² JPC=9.4 Hz, 9H, PMe₃), 1.10 (d, ³ JHH=6.3 Hz,12H, CHMe₂), -0.27 (s, 3H, AlMe). 31P NMR (CD₂ Cl₂ : δ -34.55 (s, PMe₃).¹³ C NMR (CD₂ Cl₂): δ 180.6 (s, CMe), 45.5 (d, ¹ JCH=131.1 Hz, CHMe₂),25.3 (q, ¹ JCH=121.0 Hz, CHMe₂), 12.4 (q, ¹ JCH=124.7 Hz, CMe), 9.1 (dq,¹ JPC=29.6 Hz, ¹ JCH=127.6 Hz, PMe₃), -12.8 (br q, ¹ JCH=109.6 Hz,AlMe).

Based upon the above synthesis illustration Examples 1-16, it can beseen that the cationic aluminum alkyl complexes are prepared by reactinga neutral precursor complex of the type R² C(NR¹)(NR³)AlX₂, where R¹,R², R³ and X are as defined above, with an activator compound which iscapable of abstracting one X-group from the precursor complex or ofcleaving one Al--X bond of the precursor complex. Additionally, example15 shows that the {MeC(N^(i) Pr)₂ }AlMe₂ moiety of [({MeC(N^(i) Pr)₂}AlMe)₂ (μ-Me][MeB(C₆ F₅)₃ ] can be displaced by the Lewis base PMe₃,and example 16 shows that the NMe₂ Ph group of [{MeC(N^(i) Pr)₂}AlMe(NMe₂ Ph)][B(C₆ F₅)₄ ] can be displaced by PMe₃.

The following two additional examples illustrate the preparation ofbase-free cations.

EXAMPLE 17 [{^(t) BuC(N^(i) Pr)₂ }AlMe][MeB(C₆ F₅)₃ ]

A solution of {^(t) BuC(N^(i) Pr)₂ }AlMe₂ (0.040 g, 0.17 mmol) intoluene (1.5 cm³) was prepared in the dry box. This was added dropwisevia pipette to a solution of 1 equiv B(C₆ F₅)₃ (0.087 g, 0.17 mmol) alsoin toluene (2.5 cm³) that was rapidly stirring in an ampoule fitted witha teflon tap. The ampoule was sealed and the mixture was removed fromthe dry box and stirred on a vacuum line for 30 mins. The volatiles werethen removed under reduced pressure, leaving an off-white, oily residue.(CD₂ Cl)₂ was added to this residue and the solution transferred to anNMR tube. The ¹ H NMR spectrum was recorded immediately and showedcomplete conversion to the desired base-free cation [{^(t) BuC(N^(i)Pr)₂ }AlMe][MeB(C₆ F₅)₃ ]. ¹ H NMR (CD₂ Cl)₂ : δ 4.12 (sept,³ J_(HH)=6.2 Hz, 2H, CHMe₂), 1.67 (br s, 3H, BCH₃), 1.42 (s, 9H, CMe₃), 1.09(d,³ J_(HH) =6.2 Hz, CHMe₂), 0.96 (d,³ J_(HH) =6.2 Hz, CHMe₂), -0.44 (brs, 3H, AlMe). ¹³ C NMR (CD₂ Cl)₂ : -181.3 (s, CCMe₃), 46.0 (d,¹ J_(CH)=132.1 Hz, CHMe₂), 40.1 (s, CMe₃), 29.3 (q,¹ J_(CH) =122.3 Hz, CMe₃),26.4 (q,¹ J_(CH) =125.3 Hz, CHMe₂), 25.5 (q,¹ J_(CH) =121.2 Hz, CHMe₂),-8.7 (br q,¹ J_(CH) =118.1 Hz, AlMe).

EXAMPLE 18 [{^(t) BuC(NCy)₂ }AlMe][MeB(C₆ F₅)₃ ]

The product was prepared in an identical manner to that outlined above,using 0.033 g {^(t) BuC(NCy)₂ }AlMe₂ (0.10 mmol) and 0.053 g B(C₆ F₅)₃(1 equiv, 0.10 mmol). Again 100% conversion to the base-free cation wasobserved. ¹ H NMR (CD₂ Cl)₂ : δ 3.61 (m, 2H, Cy), 1.83-1.74 (br m, 4H,Cy), 1.66 (br s, 3H, BCH₃), 1.55 (br t, 4H, Cy), 1.37 (s, 9H, CMe₃),1.25-0.98 (m, 8H, Cy), 0.89-0.79 (m, 4H, Cy), -0.46 (s, 3H, AlMe). ¹³ CNMR (CD₂ Cl)₂ : δ 181.1 (s, CCMe₃), 54.1 (d,¹ J_(CH) =134.0 Hz, Cy-C₁),39.9 (S, CMe₃), 37.5 (t,¹ J_(CH) =129.0 Hz, Cy), 36.6 (t,¹ J_(CH) =126.2Hz, Cy), 29.3 (q,¹ J_(CH) =122.3 Hz, CMe₃), 25.8 (t,¹ J_(CH) =122.5 Hz,Cy), -8.5 (q,¹ J_(CH) =114.7 Hz, AlMe).

EXAMPLE 19 Polymerization Procedure for Ethylene

All polymerizations were carried out using transition metal-freeconditions, employing glass apparatus and Teflon-coated stirrer bars. Ina typical experiment, 0.02 g of {^(t) BuC(N^(i) Pr)₂ }AlMe₂ was weighedout into a glass vial in the dry box, and 3 mL of dry toluene was added.1 equiv of activator, based on the aluminum compound was weighed into aFisher-Porter bottle and ca. 50 cm³ of toluene was added. The aluminumcomplex solution was added dropwise over 2 minutes (using a pipette) tothe rapidly stirring activator solution, ensuring efficient mixing ofthe 2 components, and a constant excess of activator (to limit formationof base adduct species). The apparatus was then removed from the dry boxand connected to the polymerization equipment, consisting of an ethylenecylinder, metal vacuum line and gas purification system. This had beenpreviously evacuated to remove any residual gas from the system. Themixture was allowed to equilibrate at the temperature required for theexperiment (10-20 minutes) before the introduction of ethylene (Note,the Fisher-Porter bottle was placed under slight vacuum prior tointroduction of the ethylene, to reduce the nitrogen content within andmaximize ethylene dissolution in the solvent). The polymerization wastypically allowed to run for 60 minutes, after which time the ethyleneflow to the system was halted. The apparatus was vented in a fume hoodand disassembled. 50-80 mL of a mixture of methanol (ca. 150 mL) andconc. HCl (ca. 1.5 mL) was added to the solution to quench the reactionand the precipitate (if any) was collected by filtration. The polymerwas then washed with acidified water (ca. 1.5 mL conc. HCl in 100 mL H₂O) to ensure removal of the Al-salts, and dried in a vacuum oven at 60°C. for 2-8 hours. The weight was recorded and the activity calculated(see table).

The results of the ethylene polymerizations are summarized in the tablebelow.

    ______________________________________                                        Table of Results for Ethylene Polymerization                                  (neutral precursor complex = {.sup.t BuC(N.sup.i Pr).sub.2 }AlMe.sub.2 ;      ethylene pressure = 2 atm; solvent = toluene)                                                                         Activity                                   Activator    Time     Temp Yield PE                                                                              (g PE/mol                             Run  Compound     (mins)   (°C.)                                                                       (g)     cat/hr/atm)                           ______________________________________                                        1    B(C.sub.6 F.sub.5).sub.3                                                                   60       26   0.053   293                                   2    B(C.sub.6 F.sub.5).sub.3                                                                   60       60   0.115   697                                   3    B(C.sub.6 F.sub.5).sub.3                                                                   60       85   0.026   162                                   4    [Ph.sub.3 C] [B(C.sub.6 F.sub.5).sub.4 ]                                                   60       26   0.084   530                                   5    [Ph.sub.3 C] [B(C.sub.6 F.sub.5).sub.4 ]                                                   60       60   0.293   1177                                  6    [Ph.sub.3 C] [B(C.sub.6 F.sub.5).sub.4 ]                                                    30*     60   0.266   3183                                  7    [Ph.sub.3 C] [B(C.sub.6 F.sub.5).sub.4 ]                                                    30*     85   0.351   4145                                  ______________________________________                                         (*= solution stopped stirring due to precipitate forming therefore stoppe     after 30 mins)                                                           

As can be seen from the above, effective catalysts for alpha-olefinpolymerizations in particular are prepared that avoid any transitionmetals. It therefore can be seen that the invention accomplishes atleast all of its stated objectives.

What is claimed is:
 1. A method of polymerizing unsaturated hydrocarbonscomprising:contacting unsaturated hydrocarbon monomer with a small butcatalytically-effective promoting amount of a cationic aluminumamidinate compound of the formula: ##STR3## wherein R¹, R², and R³ areselected from the group consisting of C₁ to C₅₀ alkyl, aryl or silylgroups, X is an anionic ligand, n=0 or 1, L may or may not be present,and if present, L is a labile Lewis-base ligand or a neutral aluminumspecies which coordinates to the cation through a bridging group, and A⁻is a counterbalancing non-coordinating or weakly coordinating anion;said contact occurring under polymerizing conditions.
 2. The process ofclaim 1 wherein R¹, R² and R³ of the catalyst species are selected fromthe group consisting of C₁ to C₁₂ alkyl, aryl or silyl groups.
 3. Theprocess of claim 1 wherein X of the catalyst species is a hydride,dialkyl amido, alkoxide, aryloxide, hydrocarbyl, substitutedhydrocarbyl, halocarbyl or thiolate.
 4. The process of claim 1 whereinn=1 and L is selected from the group consisting of tetrahydrofuran,ethers, amines, alkylamines, pyridine and phosphines.
 5. The process ofclaim 1 wherein A⁻ is a boron-derived anion.
 6. The process of claim 1wherein the cationic aluminum amidinate compound is generated in situand not isolated prior to its use as a catalyst.